Disc brakes and mounting structure therefor

ABSTRACT

The invention concerns disc brakes of the kind in which only one of the friction elements is directly moved into engagement with the brake disc or other rotor, the other friction element being displaced as a result of reaction forces set up by such engagement and for this purpose being carried by a caliper member which is slidable responsive to such reaction forces. In a disc brake of this type in accordance with the present invention, the caliper is mounted for sliding movement on a first pin arranged between the caliper member and a fixed torque plate member adjoining the brake disc, rotation of the caliper member about said first pin being restrained by a second pin secured to one of said members in circumferentially spaced relation with said first pin. The second pin is located in an aperture in the other of said members by an annular eccentric bush which at least partially embraces the second pin and is slidably received in said aperture to enable tolerance in the circumferential spacing of the pins to be accommodated during assembly of the brake and to enable the drag force to be aportioned between the two pins.

United States Patent Brown 1 Aug. 8, 1972 [54] DISC BRAKES AND MOUNTINGSTRUCTURE THEREFOR [72] Inventor: Peter William Brown, 43 l-lansellDrive, Dorridge, Solihull, England [22] Filed: July 24, 1970 [21] Appl.No.2 58,089

[52] US. Cl ..l88/73.3, 188/205 A [51] Int. Cl ..Fl6d 65/00 [58] Fieldof Search ..188/205 A, 71.1, 72.4, 72.5,

[56] References Cited UNITED STATES PATENTS 3,410,372 11/1968 Hodkinsonet al....188/72.6 X 2,920,497 1] 1960 Wiken ..308l62 X 2,531,341 11/1950Meador, Jr. ..188/72.4 X 3,374,866 3/1968 Miles ..l88/73.3 X

Primary Examiner-George E. A. Halvosa Attorney-Scrivener, Parker,Scrivener and Clarke [57] ABSTRACT The invention concerns disc brakes ofthe kind in which only one of the friction elements is directly movedinto engagement with the brake disc or other rotor, the other frictionelement being displaced as a result of reaction forces set up by suchengagement and for this purpose being carried by a caliper member whichis slidable responsive to such reaction forces. In a disc brake-of thistype in accordance with the present invention, the caliper is mountedfor sliding movement on a first pin arranged between the caliper memberand a fixed torque plate member adjoining the brake disc, rotation ofthe caliper member about said first pin being restrained by a second pinsecured to one of said members in circumferentially spaced relation withsaid first pin. The second pin is located in an. aperture in the otherof said members by an annular eccentric bush which at least partiallyembraces the second pin and is slidably received in said aperture toenable tolerance in the circumferential spacing of the pins to beaccommodated during assembly of the brake and to enable the drag forceto be aportioned between the two pins.

7 Claims, 8 Drawing Figures PATENTEBAuc a can 7 3.682.277 SHEET'I 0F 4.

mmm am I 3.682.277

' same [lF4 I PATENTEDAus 8|972 34682-277 suenuofa DISC BRAKES ANDMOUNTING STRUCTURE THEREFOR This invention concerns disc brakes of thekind in which only one of the friction elements is directly moved intoengagement with the brake disc or other rotor, the other frictionelement being displaced as a result of reaction forces set up by suchengagement and for this purpose beingcarried by a caliper member whichis slidable responsive to such reaction forces. The slidable memberusually takes the form of a socalled caliper or a yoke plate on which atleast one of the friction elements, usually the indirectly operatedfriction element, is mounted.

It is known, in a disc brake of the kind described, for the calipermember to be mounted for sliding movement on a first pin arrangedbetween the caliper member and a fixed torque plate member adjoining thebrake disc, rotation of the caliper member about said first pin beingrestrained by a second pin secured to one of said members incircumferentially spaced relation with said first pin.

One object of the present invention is to provide a disc brake of theabove type in which tolerance in the circumferential spacing of thefirst and second pins can be accommodated during assembly of the brake.

A second object of the present invention is to provide a disc brake ofthe above type in which the proportion of the drag force carried by thetwo pins in operation of the brake can be predetermined during theassembly of the brake.

According to the present invention, in a disc brake of the above type,the second pin is located in an aperture in the other of said members byan annular eccentric bush which at least partially embraces said secondpin and is slidably received in said aperture.

The invention will be further described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a plan view of a disc brake embodying the invention,

FIG. 2 is an end view thereof taken from the lefthand side of FIG. 1,

FIG. 3 is a similar view taken from the right-hand side of FIG. 1,

FIG. 4 is a sectional elevation through the brake caliper;

FIGS. 5, 6 and 7 are sectional details taken respectively on the lineVV, VI-VI and VII-VII of FIG. 2; and

FIG. 8 is a view similar to FIG. 7 showing a second embodiment.

The embodiment of disc brake illustrated in the drawings comprises acaliper generally designated 10 having a body portion 12, a bridgeportion 14 and an end limb assembly 16 which together impart to thecaliper 10, a generally U-shaped configuration with the bridge portion14 straddling a brake disc 18. The end limb assembly 16 includes a pairof circumferentially spaced ears 20 depending from the bridge portion 14and jointed by a transverse beam 22 bolted to them. The front face ofthe beam 22 is shaped to present circumferentially spaced lugs 24 forlocating an indirectly operated friction pad as hereinafter described inmore detail.

The body member 12 of the caliper 10 is internally formed to provide ahydraulic cylinder within which is received a hydraulic piston 26displaceable towards the brake disc 18 responsive to hydraulic pressurein the cylinder. The piston 26 is also displaceable towards the brakedisc through a detachable strut assembly generally designated 28 andincluding a cam 30 displaceable upon angular movement of a lever 32 toapply thrust through a dolly 34 to a dome ended plunger 36 which in turnacts on a strut 38 engageable with the piston 26. The strut 38 is screwthreaded into the piston 26 so that relative rotation between them, andeffected in conventional manner responsive to wear of the brake frictionlinings, will effect adjustment of the length of the strut assembly tocompensate for that wear.

The piston 26 is arranged to act on a backplate 40 carrying a pad 42 offriction material, the backplate 40 being arranged to be guided in anaperture of a torque plate 44 fixed to a convenient part of a vehiclestructure and interposed between the body member 12 and the brake disc18. The torque plate 44 carries a pair of circumferentially spaced andaxially directed pins 46 and 48. As will be more evident from FIGS. 6and 7, the caliper 10 is mounted for sliding movement on the pins 46 and48 and such sliding movement occurs as a result of the reaction set upwhen the friction pad assembly 40, 42 is moved towards and engages thebrake disc 18 responsive to actuation by the hydraulic piston 26. As aconsequence of such movement, a second friction pad assembly comprisinga backplate 50 carrying a lining 52 of friction material is urgedtowards the disc 18 responsive to the sliding movement of the caliper.As will be noted the backplate 50 is engaged to accept the lugs 24 inthe beam 22, which are arranged to prevent both circumferential andradial displacement of the indirectly operated pad assembly.

The drag forces experienced by the friction pads are transferred in thecase of the directly operated pad-40, 42 to the torque plate 44. In thecase of the indirectly operated pad 50, 52 however, the drag forces aretransferred through the lugs 24 and the caliper to the pin 48 and thenceto the torque plate 44. The tendency of the caliper to rotate due tothis transfer of drag forces is resisted by the pin 46.

The construction and arrangement of the drag taking pin 48 will beevident from FIG. 7 which shows that the torque plate 44 has a tappedhole for receiving a threaded portion of the pin 48, which takes theform of a bolt. The face of the torque plate 44 by which the bolt isintroduced into the tapped hole is recessed to receive a tubular sleeve54 having an internal diameter such that it is radially spaced from thebolt 48 to enable the bolt to pass through it with clearance. The headof the bolt 48 clamps the sleeve 54 to the torque plate 44 so that thesleeve is loaded under compression. The sleeve 54 in turn passes througha bore in a rearwardly extending boss 1 l of the caliper body member andthe bore in the boss is relieved between its end regions so as toprovide a two point sliding contact between the boss and the sleeve.

The pin 46 will be seen from FIG. 6 to be located in an eccentric bush56 having its external surface slidably arranged in an aperture 57formed to receive it in the caliper body, whereby the bush serves assupport means for the pin relative to the aperture.

It is to be noted that with this arrangement of the pin 46 and theeccentric bush 56, since the axis of the pin 46 and the axis of the bush56 are substantially in line in the radial direction, there can besubstantially no radial movement of the caliper relative to the torqueplate since the bush 56 will not rotate on the pin 46. How- I ever, thebush 56 will rotate on the pin 46 when circumferential pressure isapplied so that the pin and bush act as a circumferential slot in whichthe pin is slidable.

movement of the caliper is allowed and rotational flop is negligible.

Furthermore the eccentric bush 56 can be of a relatively non-corrodablematerial such as a synthetic polymer material for example nylon, wherebyto alleviate the problem of corrosion or a welding reaction between thebearing surfaces which can occur when these surfaces are both metallic.Alternatively, the eccentric bush can be made of compressible orresilient material so that any'brake drag from the caliper to betransmitted to the torque plate must be substantially transmitted by thepin 48 and not the pin 46.

It is also possible to utilize an eccentric bush, such as the bush 56,to preselect the proportion of the drag force'taken by the two pins46,48. The drag force is the resultant of the frictional forces producedby the engagement of the indirectly actuated brake pad and the brakedisc or rotor, which resultant acts along a line known as the drag line.During a braking operation, the brake force acts in a generallyhorizontal direction (FIG; 2) on the brake padsand must be balanced byreaction forces exerted through the pins 46 and 48. The

force on the trailing pin 46 must act inthe direction of the linejoining the center of that pin with the center of the eccentric bush 56,otherwise the latter would rotate, assuming negligible pin to bush andbush to bearing frictional resistance. Therefore by projecting this lineonto the drag line through which the brake force acts, the concurrentpoint of all the forces can be determined. Thus, assuming that thespacing between the centers of the apertures 55 and 57 in the caliper l0are fixed, if the spacing between the centers of the pins 46, 48 isaltered so that the eccentric bush has to rotate to a different positionto accommodate the pins, it is apparent that the reaction force on thetrailing pin 46 Similarly, taking into account the pin to bush and bushto hearing frictional resistance, it is possible to :preselect theangular position of the eccentric bush to retain the preselectedproportions of drag force to be taken by each pin.

Although the embodiment described and its variations, show the pinsattached to the torque plate 44, the caliper 10 being slidable on thepins so as to be movable relative to the fixed torque plate, the pins46, 48 could in all cases be equally well fastened to the caliper. Inthis case the torque plate would be provided with suitable apertures orbores for slidably receiving the pins.

In the embodiment described, a seal 27 for the piston 26 is located inthe wall of the hydraulic cylinder adjacent the open end of the cylinderbore. This necessitates that the axial length of the cylinder bore isrelatively great since the axial distance from the back internal wall ofthe cylinder to the seal must be at least three friction pad thicknessesin order to allow efficient' working in the maximum worn condition and afurther portion is necessary for piston guiding purposes. If however,the seal is carried by the piston, a shorter cylinder length is possiblewhich means that a thicker and stronger torque plate can be accommodatedin a brake of the same axial dimension.

It is envisaged thatthe support means locating the trailing pin 46 inthe aperture 57 could comprise means other than an annular sleeve. Forexample, the sleeve could be replaced by a plurality of resilientsupport means angularly disposed around the wall'of the. aperture 57which support the pin 46 relative to this aperture.

The means of mounting the sleeve 54 relative to the torque plate 44 inthe embodiment illustrated'is by. means of the bolt 48 which clamps thesleeve 54 to the torque plate 44 so that the sleeve 54 is loaded undercompression. An alternative way of mounting the sleeve 54 is shown inFIG. 8. A sleeve 54 is provided at its end remote from the torque plate44 with an internal screw-thread 62. The bolt 48 is replaced by anelongate stud 48 which is correspondingly screw-threaded at 60. The stud48 is screwed through the screw-threaded aperture 64 in the torqueplate, normally occupied by the bolt 48, from the side of the torqueplate remote from the sleeve, until the head 66 of the stud is hard upagainst the torque plate. The sleeve 54" is then introduced over thestud so that its unthreaded end faces the torque plate. The length ofthe stud is arranged to be such that it can engage the threads on thesleeve which is then rotated to bring it into engagement with the torqueplate in an annular groove therein. When the stud is then rotated in' adirection to retract it from the torque plate, a compressive strain isapplied to the sleeve..The head 66 of the stud 48' can be arranged toshear ofi when a predetermined strain has been applied to the sleevewhereby the sleeve is rigidly held relative to the torque plate.

I claim:

1. In a disc brake of the type in which only one of a pair of frictionelements is directly moved into engagement with the brake disc; theother friction element being displaced as the result of reaction forcesset up by such engagement and for this purpose being carried by acaliper member, in combination with said caliper 7 restraining rotationof the caliper member about said first pin, means defining an aperturein the other of said members, and an annular eccentric bush slidablyreceived in said aperture and at least partially embracing said secondpin.

2. A disc brake according to claim 1, in which said second pin is ofcircular cross-section, and said annular eccentric bush has an innerdiameter substantially that of the outer diameter of said second pin andan outer diameter substantially that of said aperture.

3. A disc brake according to claim 2 in which said aperture is locatedin the caliper member and the eccentric bush is freely rotatable withinsaid aperture whereby tolerance in the circumferential spacing of saidfirst and second pins can be accommodated during assembly of the brakeby rotation of the eccentric bush within said aperture to shift the axisof the aperture in the eccentric bush which receives said second pininto line with the axis of that pin.

4. A disc brake according to claim 2 in which said aperture is locatedin the caliper member and the eccentric bush is freely rotatable withinsaid aperture, the spacing of said first and second pins beingpreselected during assembly of the brake to achieve a particularorientation of the eccentric bush relative to said second pin and saidaperture, whereby the trailing pin is made to take off a predeterminedproportion of the drag force.

5. A disc brake according to claim 2 in which said first pin comprises asleeve and a bolt which clamps the sleeve to the torque plate so thatthe sleeve is under compression.

6. A disc brake according to claim 2 in which said first pin comprises asleeve and an elongated screwthreaded stud which engages correspondinginternal screw threads on said sleeve located at the end of the sleeveremote from said torque plate for clamping said sleeve to said torqueplate.

7. A disc brake according to claim 6 in which said stud is initiallyprovided with a head to enable the stud to be screwed into said torqueplate in a manner to apply a compressive load to said sleeve, said headbeing arranged to shear ofi the stud when a predetermined compressiveload has been applied to'said sleeve.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO. 3 ,682,277' Dated August 8, 1972 Inventor(s) Peter William Brown It iscertified that error appears in the above-identified patent 1 and thatsaid Letters Patent are hereby corrected as shown below: I

On the cover sheet insert [73] Assignee:

Girling Limited, Birmingham, England, a corporation of Great Britain .v

Signed and sealed this ZOth day of Marchjl973.

" (sEAL) Attest: v

EDWARD M.FLETCHER,JR-. 1 ROBERT J GOTTSCHALK v Attesting Officer ICommissioner of Patents ORM Po-mso (10-69) 1 USCOMM-DC 60376-P69 Q U,S.GOVERNMENT PRINTING OFFICE: I969 0-366-334.

1. In a disc brake of the type in which only one of a pair of frictionelements is directly moved into engagement with the brake disc; theother friction element being displaced as the result of reaction forcesset up by such engagement and for this purpose being carried by acaliper member, in combination with said caliper member, a first pinarranged between the caliper member and a fixed torque plate memberadjacent the brake disc and slidably mounting said caliper member, asecond pin secured to one of said members in circumferentially spacedrelation with said first pin for restraining rotation of the calipermember about said first pin, means defining an aperture in the other ofsaid members, and an annular eccentric bush slidably received in saidaperture and at least partially embracing said second pin.
 2. A discbrake according to claim 1, in which said second pin is of circularcross-section, and said annular eccentric bush has an inner diametersubstantially that of the outer diameter of said second pin and an outerdiameter substantially that of said aperture.
 3. A disc brake accordingto claim 2 in which said aperture is located in the caliper member andthe eccentric bush is freely rotatable within said aperture wherebytolerance in the circumferential spacing of said first and second pinscan be accommodated during assembly of the brake by rotation of theeccentric bush within said aperture to shift the axis of the aperture inthe eccentric bush which receives said second pin into line with theaxis of that pin.
 4. A disc brake according to claim 2 in which saidaperture is located in the caliper member and the eccentric bush isfreely rotatable within said aperture, the spacing of said first andsecond pins being Preselected during assembly of the brake to achieve aparticular orientation of the eccentric bush relative to said second pinand said aperture, whereby the trailing pin is made to take off apredetermined proportion of the drag force.
 5. A disc brake according toclaim 2 in which said first pin comprises a sleeve and a bolt whichclamps the sleeve to the torque plate so that the sleeve is undercompression.
 6. A disc brake according to claim 2 in which said firstpin comprises a sleeve and an elongated screw-threaded stud whichengages corresponding internal screw threads on said sleeve located atthe end of the sleeve remote from said torque plate for clamping saidsleeve to said torque plate.
 7. A disc brake according to claim 6 inwhich said stud is initially provided with a head to enable the stud tobe screwed into said torque plate in a manner to apply a compressiveload to said sleeve, said head being arranged to shear off the stud whena predetermined compressive load has been applied to said sleeve.